Hi Eric --
--- In "eric.robishaw" <> wrote:
>
> According to the 7800 docs, the 7800's COM3 header has 2 serial ports
> (ttts4, ttts5).
>
> I'm currently able to use ttts4, but want to take advantage of
> RTS/CTS, which the manual lists as being available for this port on
> the RTS/CTS lines (7/8).
>
> However, the docs also indicate ttts5 TX/RX on header 3 is using these
> same pins (7/8). So, which is it?
>
> Are pins 7/8
> RTS/CTS for ttts4 OR
> RX/TX for ttts5
Well, yes :). Looking at the schematic, pins 7&8 on COM3 header use
half of a SIPEX dual RS-232 level converter. Pins 2&3 use the other
half. The lever converter is fed by the CPLD, designed by TS. In
other words, it looks like pins 7&8 can be configured to run either as
RTS/CTS for ttts4 or RX/TX for ttts5.
If you want RTS/CTS for ttts4, then ttts5 must be disabled, which
means (at least) you want to write 0x7 into the ttts5 baud speed
register, as shown in the preliminary manual. But I suspect that's
not enough.
Looking through:
ftp://ftp.embeddedarm.com/ts-arm-sbc/ts-7800-linux/docs/ts-7800-syscon-regmap.txt
and we find:
* base + 0xc: ISA control and UART control (R/W)
* bit 5-0: ISA strobe length (number of extra 10nS periods)
* bit 9-6: ISA setup length (number of extra 10nS periods)
* bit 10: Honor ISA 0WS/ENDX signal (1 - honor 0WS)
* bit 11: TS special ISA pinout enable
* bit 12: ISA oscillator select
* 0 - OSC PC104 signal is a high-jitter approximation of 14.318Mhz
* 1 - OSC PC104 signal is a clean 25Mhz
* bit 13: UART RTS for COM1 header (first CPU serial port)
* bit 14: UART DTR for COM1 header (first CPU serial port)
* bit 15: RS485/RS422 control
* 1 - single RS422 using TS-UART#2 on COM2 header
* 0 - dual RS485 using TS-UART#2 and TS-UART#3
* bit 16: UART RTS for COM3 header
* bit 31-17: reserved
and later:
* * TS-UART#4 is a RS232 UART on the COM3 header. If TS-UART#5 is
* not enabled, the RTS and CTS lines can be used for flow control
* by manipulating bit 16, reg 0xc for RTS and bit 17, reg 0xc for
* CTS. XXX: TODO
*
* * TS-UART#5 is a RS232 UART that uses the RTS and CTS flow control
* signals on the COM3 header. When enabled, bit 16 reg 0xc has no
* effect on the header as it is used instead as this UART's TX
* signal.
So, it looks to me like you must also write a 1 to bits 16 and 17 at
BASE + 0x0c. But bit 17 is listed as reserved.
But, the note about TS-UART#5 also using RTS & CTS is confusing and
conflicts with other data. Given that, and the XXX: TODO note above,
I think it's best if you ask TS directly. Hopefully they can clear up
the documentation and even add the switching function you need to the
ts7800ctl utility.
Regards, ........ Charlie
>
> I've tried looking at the schematics, but can't make heads or tails.
>
>
>
>
> Eric
>
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